With a method called dead-reckoning navigation used for vehicle position estimation, the vehicle position is estimated by sequentially adding a traveling direction and a speed of the vehicle, which are calculated based on a value of measurement by an inertial sensor such as a gyro or an acceleration sensor. With this dead-reckoning navigation, position estimation difference is gradually cumulated, and thus measurement accuracy of the gyro or the acceleration sensor is very important, which requires calibration of these inertial sensors and estimated position correction.
Conventionally, there has been a method of calibrating bias of the acceleration sensor, bias of the gyro, or a scale factor by using a measurement value from a sensor that directly measures a shift amount of a GPS or a vehicle (Patent Literature 1, Patent Literature 2, and Patent Literature 6). However, the sensor calibration by the GPS can no longer be used in, for example, a case where a GPS signal cannot be taken in, for example, indoors or a multi-path frequently occurring area or a case where accuracy of positioning by the GPS deteriorates. Under such circumstances, the gyro may be corrected by using, instead of the GPS, a distance sensor such as a laser range finder (LRF) or a stereo camera that measures a distance to an object at surroundings. Described in Patent Literature 3 is a method of estimating a vehicle behavior by using an LRF or a stereo camera. Moreover, described in Patent Literature 4 is a method of correcting gyro by extracting a feature point of a white line by a camera. Moreover, described in Patent Literature 5 is a technology of correcting an own vehicle position directly from an object at surroundings of a current position.
Using these technologies makes it possible to perform the position correction and correction of the bias of the sensor such as the gyro and the scale factor by the distance sensor such as the LRF or the stereo camera.